The following background description is provided to assist the understanding of the reader. None of the information provided or references cited in this background section is admitted to be prior art to the present invention.
Mission lifetimes for pulse-powered devices, such as gravity bomb fuzes, are limited by the voltage, current, and duration of the host platform's power pulse. In such platforms, a power pulse of a specific voltage and current capability may be provided to a fuze for a limited duration. A limited duration power pulse is equivalent to a discrete amount of energy; it is equivalent to an electrical energy pulse.
Existing pulse energy capture circuits transfer this pulse energy into storage capacitors. However, the theoretical limit of energy captured from a constant current source by the existing capacitor-only pulse energy capture circuits is only 50% of the energy available to be captured, as shown below:
Ecaptured=½(CV2), the total energy capture by a capacitor, where C is the value of the capacitor's capacitance, and V is the voltage across the capacitor.
Eavailable=V*I*t, the energy available to be stored, where I is the value of the current available from the source, V is the voltage available from the source, and t is the time duration of the source current pulse.
I=C(dV/dt), the current through the capacitor, where dV/dt is the rate of change of voltage across the capacitor, so solving for C and looking at a fixed increment of time:
C=(I/V)*t, therefore substituting this result into the Ecaptured equation above results in:Ecaptured=½ V*I*t, therefore, Ecaptured=½Eavailable.
In other words, with a basic capacitive storage of a constant current pulsed energy source it is theoretically possible to capture 50% of the energy available. However, in reality, only about 39% of the energy actually may be captured, due to normal losses in the various circuit elements.
A need exists for a circuit technique to increase the amount of energy captured above the 50% efficiency barrier in conventional pulse power bomb fuzes. In other applications, such as electric vehicles powered by energy storage devices, such as capacitors, a need exists to reduce recharging time.